In the field of packet-switched communications, switching network nodes are employed to direct packet traffic to appropriate network destinations. Switching network nodes may operate in a managed mode in which the switching node employs the services of a management processor, or may operate in an unmanaged mode in which the switching node operates on its own. Both modes of operation are desired as in the managed mode the management processor provides, for example, learning functionality for the switching node, while the related management overhead is not incurred in the unmanaged mode. During normal operation, main sources of traffic to and from the management processor include: data packets that cannot be parsed by hardware classification or packets that require special software support; hardware-triggered interrupts including statistics counter rollovers; insertions or deletions from the Media Access Control (MAC) address lookup table; or warnings about resource availability. There are costs associated with the development, implementation, deployment, and management of the management processor itself.
Various related solutions, described elsewhere, address issues related to management processor optimization and management overhead reductions.
One of the switching network node deployment scenarios includes stacking multiple switching network nodes typically co-located in a single equipment shelf.
A switch stack is a configuration of a group switching network nodes which collectively behave as a single logical switching network node while providing a higher aggregate throughput. For example, suppose that a single network switch 102 contains 24 Fast Ethernet ports and 4 Gigabit Ethernet ports. Although network switch 102 supports up to 6.4 Gbps, as illustrated in FIG. 1, cascading multiple such network switches 102 can increase the aggregate system throughput. The staking configuration 100 shown in FIG. 1a) delivers an aggregate throughput of 13.2 Gbps with three switching nodes 102 deployed in a ring configuration 104. The stacking configuration 110 shown in FIG. 1b) delivers an aggregate throughput of 22.4 Gbps with six switching nodes 102 deployed in a dual ring configuration (104). And, the stacking configuration 120 shown in FIG. 1c) delivers an aggregate throughput of 17.6 Gbps with three switching nodes 102 deployed in a star configuration.
Although the increase in aggregate throughput makes stacking deployments highly desirable, it suffers from a difficulty of configuring and controlling the switching nodes 102 that in such a stack.
FIG. 2 illustrates prior art managed switching node deployments. The deployment 200 illustrated in FIG. 2a), shows each switching node 102 having an individual management processor 204 controlling thereof. While this is a simple approach it is also costly. The deployment 210 illustrated in FIG. 2b), shows the entire switching node stack being controlled by a single management processor 206. In accordance with this approach, the management processor 206 is said to enable control and configuration for the single domain defined by the switching nodes 102 in the stack. The management processor 206 sends signals or messages to all the switching nodes 102 in the stack via a separate control plane 208, usually implemented as a shared medium. As is apparent from FIG. 2a) and FIG. 2b) each switching node 102 reserves a dedicated port for retaining services of the management processor 204/206 and the shared management processor deployment 210 suffers from an overhead incurred in deploying, configuring, managing, and maintaining the shared medium 208.
There therefore is a need to solve the above mentioned issues in providing switching node control and configuration in a stack of switching nodes.